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([2405:201:682f:3094:10a6:37a8:772f:4db1]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-336bfcfc8c3sm2071443a91.11.2025.09.29.00.56.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Sep 2025 00:56:49 -0700 (PDT) From: Deepanshu Kartikey To: kent.overstreet@linux.dev Cc: linux-bcachefs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] bcachefs: Fix deadlocks between fallocate and readahead Date: Mon, 29 Sep 2025 13:26:43 +0530 Message-ID: <20250929075644.338686-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit I found that bchfs_fallocate() only evicts pagecache when FALLOC_FL_ZERO_RANGE is set: if (mode & FALLOC_FL_ZERO_RANGE) { ret = bch2_truncate_folios(inode, offset, end); truncate_pagecache_range(&inode->v, offset, end - 1); } So basic fallocate (mode=0 or just KEEP_SIZE) doesn't evict pages and shouldn't need pagecache_block_get(). Should the fix be to only acquire pagecache_block_get() for modes that actually evict (ZERO_RANGE, PUNCH_HOLE, INSERT/COLLAPSE)?